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May 2011 Archive for Ask an Agronomist

RSS By: Farm Journal Agronomists, Farm Journal

Have your agronomic questions answered by a Farm Journal agronomist. E-mail us directly at TestPlots@FarmJournal.com, and we’ll respond on this blog to provide an interactive dialogue.

Have You Tested This Foliar Fertilizer Tool?

May 31, 2011

Question: Have you ever done any testing on Kugler XRN?

Answer: I have not done any testing on Kugler XRN. Its main use is for foliar fertilizer. If you are looking at using the product I would suggest using it as an additional fertilizer source, not to replace any of your current nitrogen program. It looks like the application timing may line up with other treatments being applied to the field, so you may be able to add it in as a tank mix. You can find more information on use rate and timing on their website. I would suggest putting some of your own plots out this year if you are interested in looking at the product.
 
 
 
This blog is provided as an interactive way for you to have your questions answered by our Farm Journal Agronomists. E-mail your nitrogen, soil fertility, soil density, planter set-up, scouting, and other questions to: TestPlots@FarmJournal.com.
 

Would Placing Fertilizer In The Row Be Good For Soybeans?

May 24, 2011

Question: I plant soybeans after corn that was grown with a covering of manure, 100# urea and 200# starter. I do not fertilize them and have been satisfied with the results. Would putting fertilizer in the row when planting soybeans be a good idea? If so, what kind and how much?

Answer: Soybeans are big users of potash and use a fair amount of phosphorus. Crop removal rates for soybeans can give you some indication of fertilizer needs; however, soil testing is very important. A 50 bu/a soybean crop removes 72.5 lb K20 which is equal to 121 lbs potash (0-0-60) per acre. A 50 bu/a soybean crop removes 42.5 lb P2O5 which is equal to 82 lbs of MAP (11-52-0). These values are just crop removal rates and do not take into consideration soil test values. The best thing to do is pull some soil samples and determine if your levels are low, medium or high. For example, if you have very high P levels from a history of manure application you may not need to apply any phosphorus for the soybeans. Soybean seed is very sensitive to injury from fertilizer, so I would be very cautious on applying much fertilizer with the planter. If you need high rates of potash you would want to apply broadcast applications. Contact your local extension office or university on soil testing instructions and finding a local lab. 
 
 
 
This blog is provided as an interactive way for you to have your questions answered by our Farm Journal Agronomists. E-mail your nitrogen, soil fertility, soil density, planter set-up, scouting, and other questions to: TestPlots@FarmJournal.com.
 
 

Should I Include Sulfur For Soybeans Or Only For Corn?

May 20, 2011

Question: I'm in a corn, corn, soybean three-year rotation and currently am only applying sulfur on the two years of corn. Should I be adding it to the bean year? Or, would it be available to the beans if I were to up the rates to more than what the corn needs in the corn years? 

Answer:  A 200-bushel per acre corn crop has a sulfur removal rate around 15 lb/A. In recent years there has been a greater yield response to applying sulfur for corn production. Soil fertility specialists believe the sulfur response is increasing because of the reduction of sulfur atmospheric deposition (cleaner air, less pollution). Also, fertilizer sources are cleaner (less incidental sulfur in them) and with fewer manure applications. Soybeans are typically not very responsive to sulfur applications. Generally, soybeans can maintain adequate levels in the plant by using residual levels from the soil. I would continue applying sulfur just for your corn production and not the soybeans. However, it may be helpful to pull some tissue tests in soybeans to verify adequate levels. Sulfur fertilizer in general is very mobile in the soil and would likely not be available in subsequent years. 
 
Be on the lookout for sulfur deficiencies in your crops.
 
You can easily misdiagnose this problem.
 
This blog is provided as an interactive way for you to have your questions answered by our Farm Journal Agronomists. E-mail your nitrogen, soil fertility, soil density, planter set-up, scouting, and other questions to: TestPlots@FarmJournal.com.
 

How Much Of My Nitrogen Is Still Available For Use?

May 16, 2011

We have received a number of questions this spring pertaining to nitrogen loss.  The following article, written by Fabian G. Fernandez, University of Illinois, addresses many of the concerns farmers are facing as they deal with wet soils.

Wet soil conditions in the spring always create concerns that nitrogen (N) applied last fall for the new corn crop might be lost. The most important thing to remember is that when soils become saturated, the potential for N losses is directly related to the amount of N present in the nitrate (NO3-) form. Under water-saturated conditions, nitrate is most likely to be lost through denitrification in fine-textured soils and through leaching below the root zone in coarse-textured or intensively tiled soils.
 
Most fall-applied N is either ammonium (NH4+) or a form that transforms rapidly into ammonium. Nitrification, the conversion of ammonium to nitrate, is a bacteria-mediated transformation. The bacterium Nitrosomonas converts NH4+ into nitrite (NO2-), while the bacterium Nitrobacter converts NO2- to NO3-. The activity of these bacteria is minimal at temperatures below 50°F. The bacteria also need aerobic conditions (when soil is not water-saturated) to nitrify ammonium. The amount of nitrification that occurs in the soil thus depends largely on soil temperature and the time elapsed between application and when the soil becomes saturated with water. Further, the nitrification process can be reduced with the use of nitrification inhibitors that lower the activity of the bacteria and allow N to stay in the ammonium form for a longer period. The greatest reason for concern about N losses at this time, or for most any given year, would be if fall N application guidelines were not followed. Last fall was warm well into the end of October and first part of November, with soil temperatures at the 4-inch depth dropping below 50°F later than normal. If fall application recommendations were not followed, there is a greater chance that some of the N might have been transformed to nitrate and potentially lost. Another reason for having concern would be if nonrecommended sources of fall N, such as urea, ammonium nitrate, or urea-ammonium nitrate solutions (UAN), were used.
 
While air temperatures were warm for a long time in the fall, once soil temperatures dropped below 50°F to allow N applications, the air temperatures remained low. That leads me to speculate that where N was applied correctly last fall, there was very little chance for nitrification. I suspect that any nitrate that was present before soils froze was probably retained in the soil until spring, because much of winter's precipitation did not move through the soil because it was frozen. Since soils have thawed, however, we have had a lot of precipitation, and I suspect some nitrate in soil has been leached out. But as I mentioned, I suspect there was not much nitrate to begin with. Since soils have been cool and wet until just recently, and nitrifying bacteria need warm temperatures and aerobic conditions to transform ammonium to nitrate, it is likely that not much fertilizer N has been transformed to nitrate or soil N mineralized at this point.
 
Last week we collected soil samples from depth increments of 0 to 6 inches and 6 to 12 inches to measure ammonium, nitrate, and total inorganic N (the sum of ammonium and nitrate). This was done from the zero N (control) plot and the plots receiving 160 lb N/acre as anhydrous ammonia, with N-Serve applied 6 inches below the soil surface the first week of November last year. These plots are located near Urbana, and the soils are silty clay loam.
 
Nitrogen Recovery
Percent ammonium, nitrate, and total inorganic N (ammonium plus nitrate) recovered in soil at the beginning of May from fall-applied N.

I estimated percent N recovery by subtracting soil N in the control plot from that in the plot treated with 160 lb N/acre and dividing by the application rate of 160 lb N/acre. I present these data to provide some general information, but the values are not absolute and should be considered so, because many factors impact N recovery. Figure 2 shows that 26% of the total N was recovered within the top 6 inches of the soil and 28% within the top 12 inches. The figure also shows that 17% of the applied N is still in the ammonium form and that most N is still present in the top 6 inches of the soil, with very little movement of nitrate into the 6- to 12-inch increment. These values represent typical recovery values observed in other recent studies at a similar sampling time. For instance, percent recovery from fall-applied N was 22% and 23% in two very wet years and 54% in a year with a dry spring with low potential for N loss. Across all three years of that study, N recovery was 33%, and average loss of corn yield relative to the economical optimum N rate was less than 2%.--Fabián G. Fernández
 

What Is Your Opinion On Vertical Tillage?

May 13, 2011

Question: I’m wondering what your opinion is about vertical tillage tools such as a Summer’s super coulter? I have always believed that a disk packs the soil--does a straight blade not do the same? I am from west-central Minnesota, and we have heavy soils here.  These tools are getting more popular around here. I have been renting one because they do leave a beautiful seed bed, but is there a compaction layer from them? Trying to decide whether to buy one and give up my field cultivator.

Answer: The idea behind vertical tillage is hat the blades or coulters are not moving soil in a sideways direction. A traditional disk blade is concave and moves soil in a horizontal direction. Tools that shear the soil can create a density layer, depending on the conditions. It is common for a disk, field cultivator and moldboard plow to create a soil density layer. There are several vertical tillage tools on the market that prepare the seed bed and do not create density layers. You need to keep in mind that creating a good seed bed is still most important. You need a uniform, level seed bed in order to maintain good ear counts. Keep in mind that your primary tillage (if you’re doing any) plays a role in a vertical tillage system as well.   Your primary tillage needs to have uniform shatter under the ground while leaving the surface relatively smooth. A vertical tillage tool typically does not move as much soil as a disk, so its ability to level a rough surface is limited. I would also suggest doing some digging and analyzing root growth to see if you are being affected by soil density layers. 
 
 
This blog is provided as an interactive way for you to have your questions answered by our Farm Journal Agronomists. E-mail your nitrogen, soil fertility, soil density, planter set-up, scouting, and other questions to: TestPlots@FarmJournal.com.
 
 

How To Set Down Pressure in a Wet Spring

May 06, 2011

Question: I attended one of the corn college planter clinics and forgot to ask about how the weight of seed in the seed box affects my down pressure. I was also wondering how much is too much in a wet spring?  I have a White 8202 planter with standard springs and the options are 50,60,105 and 115 lbs and we use it in a corn/soybean rotation with conventional tillage. I understand I should set it for the toughest part of the field that I'm in and check it like they described but I'm struggling with deciding on what that setting should be.

Answer: In conventional tillage, you are ideally planting into 4" of uniform soil behind your soil finisher. If the seedbed is not uniform or you are planting too fast, then that will require more down pressure. Typically, if the conventional tillage is done properly, the weight of the row unit plus the weight of a full seed box will be enough down pressure. However, it could be very likely that you'll need to carry between 50 to 100 lb. of down pressure.
To review, down pressure does two things: it maintains the depth of the disc openers and it ensures a true V. To check if you are achieving a true V, secure one of the press wheels up with a strap. Then run the planter and check to see if its a nice true V on both sides.
Setting down pressure correctly often demands walking a fine line and making on-the-go decisions. Sidewall smearing occurs when too much down pressure compacts the soil around the seed and brings dry soil on top of the seed. This can lead to uneven emergence. Too little down pressure will mean you do not maintain depth or close the slot behind the planter.
Also, you may want to read this step-by-step description of planter settings: http://www.agweb.com/article/Down_Pressure_Quiz_How_Much_is_Enough_193439/
This blog is provided as an interactive way for you to have your questions answered by our Farm Journal Agronomists. E-mail your nitrogen, soil fertility, soil density, planter set-up, scouting, and other questions to: TestPlots@FarmJournal.com.
 

Will Corn Totally Under Water Survive?

May 04, 2011

Question: I farm in northeast Arkansas. This is my first year for corn. We have been getting hammered with rain all week. I have been running two 12" relifts all week in order to keep the water off of the corn. The ground has been muddy for 7 days but my corn is up on beds, so it has been doing ok. The corn is in the 4-5 leaf stage. We got 5 inches of rain today, and now it is under water. Some of it is completely covered while the rest is only half under water. Now my question: How long will corn survive under water? I have to decide tomorrow morning whether to try to pump it off again or let it go. We have heavy rain forecast for tonight and tomorrow. The river and ditches are overflowing, but I have a road (levee) around the field so I can still pump some of it off. Will the corn be ok if I can get it out of the water by tomorrow night? The ground will still be muddy for several days, possibly weeks. Am I fighting a losing battle, or do I keep fighting? I have no experience with corn so any advice will be appreciated.

Answer:When corn is in the 4-5 leaf stage with this kind of water, my experience has been that its survival and quality of survival will depend on your current air-soil temperatures.  If the temperatures are in the 45- to 60-degree range, the corn could actually survive being under water for about three days.  If the temperature is in the 65- to 80-degree range, however, the plant respiration is so high that after 24 hours there would be a lot of damage.  The other problem you have is that any time water goes over the top of corn there will be soil that gets down into the whorl of the corn.  The soil that gets in to the whorl contributes to crazy top in the corn, so even if it survives there’ll be a percentage of that corn that will be negatively impacted.  If the tops are sticking out and only the base is covered, then you probably have about three days of leeway.  If it’s completely under water and temperatures are warm, your window is pretty limited. I am posting links to some additional online resources for your consideration and evaluation. Best of luck to you as you address this tough situation.
 
 
 
This blog is provided as an interactive way for you to have your questions answered by our Farm Journal Agronomists. E-mail your nitrogen, soil fertility, soil density, planter set-up, scouting, and other questions to: TestPlots@FarmJournal.com.
 

How Can I Effectively Dual-Apply Anhydrous Ammonia Preplant?

May 02, 2011

Question: I'm currently dual applying anhydrous ammonia preplant with 12-0-0-26 (different pump, same knife). I'm thinking of adding a nitrogen stabilizer. I can add nitrapyrin to the ammonia (N-serve) or to the 12-0-0-26 (Instinct). If I add it to the 12-0-0-26 and it is injected in the ground right above the ammonia, will it stabilize the ammonia along with the 12 parts in the liquid?

Answer: You may want to check with your local Dow AgroSciences rep. Here is some info I gathered from Dow on this issue. Since nitrapyrin inhibits nitrosomonas bacteria in the soil and does not actually “treat” the nitrogen, an application of nitrapyrin would stabilize both of his nitrogen sources IF both sources are in soil that is treated with nitrapyrin.  In this situation, it would be best to stabilize the ammonia with N-Serve. I’m assuming that a larger portion of your nitrogen is in the ammonia versus the 12-0-0-26. The N-Serve will move throughout the ammonia band in the soil and that will likely include the soil where the 12-0-0-26 is applied as well, so both sources would be stabilized.
 

 

This blog is provided as an interactive way for you to have your questions answered by our Farm Journal Agronomists. E-mail your nitrogen, soil fertility, soil density, planter set-up, scouting, and other questions to: TestPlots@FarmJournal.com.

 
 
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